/**
 * 浏览器嗅探，采用传统的userAgent
 * 
 */
B = function(ua){
	var b = {
		ie: /msie/.test(ua) && !/opera/.test(ua),
		opera: /opera/.test(ua),
		safari: /webkit/.test(ua) && !/chrome/.test(ua),
		firefox: /firefox/.test(ua),
		chrome: /chrome/.test(ua),
		maxthon: /maxthon/.test(ua),
		sogou: /se/.test(ua),
		tt: /TencentTraveler/.test(ua)
	};
	var mark = '';
	for (var i in b) {
		if (b[i]) { mark = "safari" == i ? "version" : i; break; }
	}
	b.version = mark && RegExp("(?:" + mark + ")[\\/: ]([\\d.]+)").test(ua) ? RegExp.$1 : "0";
	b.ie6 = b.msie && parseInt(b.version, 10) == 6;
	b.ie7 = b.msie && parseInt(b.version, 10) == 7;
	b.ie8 = b.msie && parseInt(b.version, 10) == 8;
	b.ie9 = b.msie && parseInt(b.version, 10) == 9;	
	return b;
}(navigator.userAgent.toLowerCase());